Humidifier for humidifying reactant gases for a polymer electrolyte fuel cell system

ABSTRACT

The present invention relates to a humidifier for humidifying reactant gases for a polymer electrolyte fuel cell system, and more particularly, to the humidifier for humidifying reactant gas which is capable of adjusting the amount of water for humidification while reducing the electric power consumption and its size, thereby maintaining an optimal temperature and humidity of the reactant gas supplied to a polymer electrolyte fuel cell. The humidifier for humidifying reactant gases comprises a humidification vessel which a reactant gas inlet pipe for supplying reactant gases thereto, a water inlet pipe for supplying water thereto, and a reactant gas supplying pipe for supplying the humidified reactant gas to the fuel cell are connected, respectively, and a spray which is installed in the humidification vessel and finely sprays the reactant gases and water which are supplied to the humidification vessel.

FIELD OF THE INVENTION

[0001] The present invention relates to a humidifier for humidifyingreactant gases for a polymer electrolyte fuel cell system, and moreparticularly, to the humidifier for humidifying reactant gases which isneeded for the development and actual operation of a polymer electrolytefuel cell system and is capable of adjusting the amount of water whilereducing the electric power consumption and its size, therebymaintaining an optimal temperature and humidity of the reactant gasessupplied to a polymer electrolyte fuel cell.

BACKGROUND OF THE INVENTION

[0002] In general, a fuel cell system, which is widely known as a kindof electric power generation system, generates an electric power byelectrochemical reactions. Such fuel cell systems have very extensiveranges of applications from small to large-sized systems for reasonsthat they work with higher energy efficiency and also produce nopollutants in contrast to the conventional combustion engines. The fuelcell systems are classified according to the kind of an electrolyte intonamely, alkaline type, phosphoric acid type, molten carbonate type,solid oxide type, polymer electrolyte type, etc.

[0003] Among the above-mentioned various types of fuel cells, thepolymer electrolyte fuel cell system is particularly suitable for anautomobile or a mobile electric power source because it has someadvantages in that it is well operable even at a relatively lowtemperature, its electrolyte is solid so that there is no danger ofleakage of the electrolyte, and its maintenance and repair areconvenient.

[0004] In this polymer electrolyte fuel cell system, the polymermembrane used as a polymer electrolyte, through which the protons (H⁺)move, must be in a sufficiently moistened condition to provide anadequate ionic conductivity. In case the electrolyte membrane isdehydrated, the fuel cell system is not normally operable due to thedegradation of its ionic conductivity. For this reason, the humidifyingprocess is indispensable to the fuel cell system to prevent theelectrolyte from drying.

[0005] The characteristics of the polymer electrolyte fuel cell systemare greatly influenced by manufacturing and operating techniques.Accordingly, the operating parameters such as temperature of a fuelcell, flow rate, pressure, and temperature of reactant gases, andhumidity should be adjusted to be in an optimal condition by means of ahumidification apparatus.

[0006] As illustrated in FIG. 1, the gas supply apparatus comprises: aninlet pipe 1 through which the reactant gases are supplied from areactant gas reservoir; a flux regulator 2 for adjusting the flow rateof supplied reactant gases; a humidifier 3 for humidifying the reactantgases; a gas supplying pipe 4 for supplying the humidified reactantgases to the fuel cell 5; a pressure regulator 7 for adjusting thepressure of reactant gases inside the fuel cell 5; an outlet pipe 6through which the reactant gases are emitted from the fuel cell 5 by theoperation of the pressure regulator 7; a fuel cell thermocouple 8 whichis installed inside the fuel cell 5 and is used in a temperature monitor10 for controlling a coolant regulator 9; and a coolant regulator 9 forcooling the fuel cell 5.

[0007] In the conventional humidifier that is commonly positionedbetween the gas supply apparatus and the fuel cell 5, as shown in FIG.2. Said humidifier, which humidifies reactant gases by passing throughthe heated water, comprises: a humidifier thermocouple 13 installed inthe middle of a humidification vessel 17; a heater 14 disposed along thecircumferential surface of the humidification vessel 17; the insulatingmaterial 15 surrounding the outer surface of the heater 14; a waterlevel gauge 16 which is installed at one side of the humidificationvessel 17 and indicates the water level of the humidification vessel 17;a gas supplying pipe 4 through which the humidified reactant gases issupplied to the fuel cell 5; and an inlet pipe 12 through which thereactant gases is supplied to the humidifier.

[0008] However, the above-described conventional humidifier is defectivein that it is difficult to adjust the size of bubbles generated insidethe humidifier and the amount of water needed for humidification,heating water consumes electric power too much, and moreover, theoverall size of the humidifier would be increased according to theincrease in the capacity of a fuel cell system.

[0009] In consideration of such mobile power supply features that itssize would be restricted and the electric power consumed by itssupplemental devices would also be minimized, the conventionalhumidifier brings several limitations in its actual applications,because it takes additional electric power for heating water in additionto the matter of increase in its overall size.

[0010] In another conventional method of humidifying reactant gasesusing a membrane, there is a drawback in that additional humidificationdevices should be mounted inside a fuel cell. As a result, the innerconstruction of a fuel cell is not only complicated but the size of afuel cell is increased. Moreover, such apparatus has another drawbackthat the humidification conditions are varied with the state of amembrane, temperature and pressure of a fuel cell.

SUMMARY OF THE INVENTION

[0011] Accordingly, in order to overcome the above-mentioned problemsoccurring in the conventional humidification apparatus, an object of thepresent invention is to provide the humidifier for humidifying reactantgases for a polymer electrolyte fuel cell system which is capable ofadjusting the amount of water for humidification while reducing theelectric power consumption and its size, thereby maintaining an optimaltemperature and humidity of the reactant gases supplied to a polymerelectrolyte fuel cell.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The above object and feature of the present invention will becomeapparent from the following description of the invention, when taken inconjunction with the accompanying drawings, in which:

[0013]FIG. 1 is a schematic view showing a gas supply apparatus and afuel cell for a general fuel cell system;

[0014]FIG. 2 is a sectional view of the conventional humidifier for afuel cell system; and

[0015]FIG. 3 is a sectional view of the humidifier for a fuel cellsystem in accordance with the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] In order to accomplish the above object, a gas supply apparatusfor a fuel cell comprises: an inlet pipe through which the reactantgases is supplied from a reactant gases reservoir; a reactant gas fluxregulator for adjusting the flow rate of supplied reactant gases; ahumidifier for humidifying the reactant gases; a reactant gas supplyingpipe for supplying the humidified reactant gases to the fuel cell; apressure regulator for adjusting the pressure of reactant gases insidethe fuel cell; a coolant regulator for cooling the fuel cell; and a fuelcell temperature monitor for obtaining the temperature of the fuel cell,where said humidifier comprises:

[0017] a humidification vessel to which a reactant gas inlet pipe forsupplying reactant gases thereto, a water inlet pipe for supplying waterthereto, and a reactant gas supplying pipe for supplying the humidifiedreactant gases to the fuel cell are connected, respectively; and

[0018] a spray which is installed in the humidification vessel andfinely sprays the reactant gases and water which are supplied to thehumidification vessel.

[0019] Hereinafter, the humidifier for humidifying reactant gases willbe described in detail with reference to the accompanying FIG. 3.

[0020]FIG. 3 is a sectional view of the humidifier for humidifyingreactant gases for a polymer electrolyte fuel cell system in accordancewith the present invention. As illustrated in FIG. 3, the humidifier forhumidifying reactant gases in accordance with the present inventioncomprises: a humidification vessel 20 connected with a reactant gasinlet pipe 24 for supplying reactant gases and a water inlet pipe 30 forsupplying water; a spray 26 for finely spaying water in thehumidification vessel 20; a reactant gas supplying pipe 24 for supplyingthe humidified reactant gases to the fuel cell 5; a water storage tankfor storing the water used in the humidification; a valve 36 forreplenishing the water storage tank with water; a water flux regulator32 for adjusting the amount of water supplied to the humidificationvessel 20 for humidification.

[0021] Herein, before the reactant gases and water, which are adjustedby the reactant gas flux regulator and the water flux regulator, aresupplied to the spray 26, they are preheated at the same temperature ofthe fuel cell during their passage along the double passages 22, 22′where the hot coolant flows.

[0022] Then, the spray 26 sprays the reactant gases and water so thatthe humidification of reactant gases is completed.

[0023] A decrease in temperature during the above spraying process iscounterbalanced with a heat transfer from the double passages 22, 22′where the hot coolant flows. In order to preventing condensation of themoisture in the humidified reactant gases and decrease in thetemperature of said reactant gases, the distance between the humidifierand the fuel cell is designed to be minimized, and simultaneously, thedual pipe 40 is introduced. By allowing the above coolant to flowthrough the exterior passage of the dual pipe 40, the condensation andcooling of the humidified reactant gases can be effectively prevented.

[0024] On the other hand, the water flux regulator is capable ofadjusting the amount of water needed for the humidification dependingupon the flow rate and temperature of the reactant gases supplied to thespray, thus saving water for humidification. The valve, which isinstalled at the water storage tank for replenishing the tank withwater, is separated from the reactant gases so that it is capable ofcontinuing to replenish the tank without ceasing operation of the fuelcell.

[0025] As described above, consequently, by adopting the way of sprayingthe reactant gases and water and heating them using the coolant heatedby the fuel cell, the humidifier of the present invention excludes theadditional energy, which is to heat water, in contrast to theconventional humidifier and also diminishes the size of humidifierregardless of the capacity of the fuel cell. In addition, the sprayingway of the present invention is capable of adjusting the amount ofreactant gases and water needed for humidification, thus saving waterfor humidification. The reactant gas supplying pipe of the presentinvention would improve the performance of given fuel cell.

[0026] Although the preferred embodiments of the present invention havebeen disclosed for illustrative purposes, those skilled in the art willappreciate that various modifications, additions and substitutions arepossible, without departing from the scope and spirit of the inventionas disclosed in the accompanying claims.

What is claimed is:
 1. In a gas supply apparatus for a polymerelectrolyte fuel cell system comprising: an inlet pipe through which thereactant gases is supplied from a reactant gas reservoir; a reactant gasflux regulator for adjusting the flow rate of supplied reactant gases; areactant gas supplying pipe for supplying the humidified reactant gasesto the fuel cell; a pressure regulator for adjusting the pressure ofreactant gases inside the fuel cell; a coolant regulator for cooling thefuel cell; a fuel cell temperature regulator for adjusting thetemperature of the fuel cell; and a humidifier for humidifying thereactant gases for a polymer electrolyte fuel cell system, saidhumidifier comprising: a humidification vessel to which a reactant gasinlet pipe for supplying reactant gas thereto, a water inlet pipe forsupplying water thereto, and a reactant gas supplying pipe for supplyingthe humidified reactant gases to the fuel cell are connected,respectively; and a spray which is installed in the humidificationvessel and finely sprays the reactant gases and water supplied to thehumidification vessel.
 2. The humidifier according to claim 1, whereinsaid humidification vessel is provided with a double passage, where acoolant heated by the fuel cell flows, in order to preheat the reactantgases introduced into the reactant gas inlet pipe.
 3. The humidifieraccording to claim 1, wherein said humidification vessel is providedwith a double passage, where hot coolant heated by the fuel cell flows,in order to preheat the water introduced into the water inlet pipe. 4.The humidifier according to claim 1, further comprising a water storagetank for storing the water supplied to the spray.
 5. The humidifieraccording to claim 4, wherein said water storage tank is equipped with avalve capable of replenishing the tank with water without ceasingoperation of the fuel cell.
 6. The humidifier according to claim 4,wherein said water storage tank is further equipped with a water fluxregulator for adjusting the amount of water supplied to the spray sothat it can vary the amount of humidification.
 7. The humidifieraccording to claim 1, wherein said humidification vessel is furtherprovided with a double passage, where hot coolant heated by the fuelcell flows, in order to heat the humidified reactant gases just after itis sprayed.
 8. The humidifier according to claim 1, wherein saidreactant gas supplying pipe is a dual pipe that is designed to allow thecoolant heated by the fuel cell to flow through the exterior passagethereof in order to maintain the temperature and pressure of thehumidified reactant gases to be uniform.